Magnetic hammer



Dec. 16, 1958 R. A. scHoLTEN MAGNETIC HAMMER Filed March .'50, 1956 57 ifo w United States Patent() MAGNETIC HAlVIMER Richard A. Scholten, Valparaiso, Ind., assignor to The Indiana Steel Products Company, Valparaiso, Ind., a corporation of Indiana f Application March 30, 1956, Serial No. 575,155

7 Claims. (Cl. 145-30) The present invention relates to improvements in magnetic hammer structures arranged to hold a tack, nail or the like by magnetic attraction prior to driving the nail or tack home.

While there have been numerous types of magnetic hammers proposed in the past, such prior magnetic structures frequently have the disadvantages of being cumbersome, fragile, or excessively large to be received conveniently in the head of a small hammer.

The hammer structure of the present invention provides a small, highly etiicient magnetic holding means which makes it readily adaptable to small hammers such as tack hammers.

In the hammer assembly of the present invention, a strongly magnetic permanent magnet is combined with a magnetic flux concentrating means to make most eflicient use of the magnetic energy. With the specific structural arrangements of the present invention, the entire magnetic assembly can be made extremely small, lightweight, and resistant to impact.

An object of the present invention is to provide an improved magnetic hammer assembly having the advantages of light weight and small size.

Another object of the invention is to provide an improved hammer assembly of the magnetic type having a highly eicient magnetic circuit.

Still another object of the invention is to provide a magnetic hammer assembly which is economical to manufacture.

These and other objects of the invention, as well as various features thereof, will be apparent to those skilled in the art from the following description of the attached sheet of drawings which illustrate several embodiments of the invention.

In the drawings:

`Figure 1 is a fragmentary view in elevation, and partly in cross section, illustrating one form of the present invention; I

Figure 2 is a side view in elevation of the hammer assembly shown in Figure l;

Figure 3 is a fragmentary view in elevation, and partly in cross section, illustrating a modified form of the invention;

Figure 4 is a cross-sectional view taken substantially along the line 4-4 of Figure 3;

Figure 5 is a-view taken substantially on line 5-5 of Figure 6 of a hammer head embodying a modified form of the invention;

Figure 6 is an end View of the hammer head illustrated in Figure 5;

Figure 7 is an end view of a still further modied form of the invention; and

Figure 8 is a fragmentary view in elevation, and partly in cross section, illustrating still another modied form of the invention.

As shown on the drawings:

In Figure l, reference number 10 indicates generally a hammer head composed of a ferromagnetic material i less steel, or the like.

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In the particular embodiment of the invention shown inA Figure 1 the striking face of the hammer head is recessed as indicated at 13 to accommodate the magnetic components. As evident from Figures 1 and 2, the magnet may consist of a permanently magnetized annular magnet i4 received in engagement with the walls of the recess 13. For most efficient results, it is desirable to employ a magnet having strong magnetic characteristics such as amagnet of the ferrite type. One suitable example of such a magnet is barium ferrite produced by compacting and sintering together about one molecular proportion of barium oxide and about six molecular proportions of ferric oxide.

Seated at the base of the recess 13 is a spacer 16 composed of a non-magnetic material such as brass, stainy 14 is magnetized in a direction which is radial with respect to the longitudinal axis of the head 10. In the illustrated embodiment, the inner periphery of the annular magnet 14 may constitute a north pole and the outer periphery a south pole.

A low reluctance path betwen the opposed portions of the magnet is provided by inserting a ferromagnetic pole piece 19 into the hollow interior of the annular magnet 14. The pole piece 19 also has a forward surface 21 which is substantially coplanar with the outer face 18 of the spacer 17 and also with the forward edge 10a of the head 10.

When the striking face of the hammer contacts a magnetizable tack 22 a low reluctance path is established between the outside periphery of the annular magnet 14, through the ferromagnetic head of the tack 22, into the ferromagnetic pole piece 19, and through the opposite or inner periphery of the magnet 14.

As best indicated in Figure l, the forward edge 10a of the hammer head 10 is suitably crimped or peened over against the non-magnetic spacer 18 to hold the assemblyv The form of the invention illustrated in Figures 3 and` 4 of the drawings is essentially identical to that described in connection with Figures l and 2 except for the fact that the magnet assembly consists of a pair of semicircular annular segments 24 and 26. assembly is somewhat easier to magnetize than the continuous ring type of magnet illustrated in Figures 1 and 2. Like the other embodiment, however, the magnets 24 and 26 are both magnetized in a direction radial with respect to the longitudinal axis of the head 10 and provide ux return paths in identically the same fashion as that previously described.

The form of the invention illustrated in Figures S and 6 of the drawings makes use of a pair of opposed, generally rectangular bar magnets 27 and 28 again magnetized in a direction which is radial with respect to the longitudinal axis of the head 10. The head 10 is provided with a rearwardly extending slot 29. A non-magnetic spacer 31 is disposed at the base of the slot 29, and rectangular non- Patented Dec. 1,6, 195,8

An annular non-magnetic spacer 17 is disposed forwardly of the permanent magnet 14 and. has a forward face 18 substantially flush with the striking This type of is a ferromagnetic pole piece 33 which provides a low reluctanceV path between the opposed magnets 27 and 2,8`

arid'whichextends between the non-niagnetic'spacers 3 2 and` 35to` providel a substantially ush Strikingfa'ce 34 whichis `coplai'iar4 with the exposed faceof the spacers and the face of thehammer head`10. A's seen in Figure 5, the forwardendof the head may` be crimpedorotherwise formed about the nonmagnetic spacers 32 and 35, as' indicated at 1019,' to holdthemagnetic structure secure1y`in place. The magnets 2,7and'28 themselves are tightly held-against thewallsV ofthe recess29by virtue of their strong magnetic attractiony and opposed spacers 31, 32 and 35 provide a Shock absorbing meansfor the magnet assembly.' Sincethe'materialof the head 10 itself provides a low reluctance path for the magnetic lines of force, itis notnecessary thatthe magnets 27 and 28 abut the non-magneticspacers 31, 32; and`35.

In order'to hold`the magnetic structure securely within the slot 29, the head'may beprovided with a pair" of opposednon-magnetic plates'36 and'37`composedof a non-magnetic metal such asV brass, stainless steel, or the like. The plates'36 and 37" may be soldered or welded in place to the hammer head 10.4

As a further alternative, as illustrated in Figure 7, of the drawings, the magnetic assembly can be held in place by'providing a rivet having a stem 39 extending through the head 10, the magnets 27 and 2S, and the pole piece 33. Theends of the rivet are upsetto form heads as indicated at42 and 43 to hold the entire magnet assembly against displacement.

In the form of the invention illustrated in Figure 8 ofy the drawings, the hammerhead 10' isprovided with a transversely` extending slot 44 open laterally and forwardly and having generally converging 'wall portions 46' and 47. A non-magnetic spacer 48 is seated against the base ofthe slot 44 and a pairof opposed at permanent magnets 49 and 51 are received by magnetic attraction against the converging walls 46 and '47. A non-magnetic forward spacer52 having a` surface 53 coplanar with the forward orfstriking face of the hammer head 10 is tightly received withinv the recess 44 by crimping `or otherwise forming the forward end 54 ofthe head 10 over the nonmagnetic spacer 52. A ferromagneticrpole member 56v conformingly bridges the space between the opposed `magnets 49 and 51, and extends throughthe non-magnetic spacer 52to provide a forward surface 57which is 'flush with the striking face of the hammer assembly. Plates, not Shown, enclose the slot 44 laterally, the same as'do plates 36 and 37 (Figure 6).

From the foregoing, it'will be apparent that the mag-v netic hammer of the present invention provides a compact but highly eicient magnetic holding assembly. The materials employed are not subject to demagnetization due to passage of time,- mechanical shock, or temperature variations lto nearly thesame extent as `the type' of magnetic hammecassemblies presently beingemployed. Furthermore, the constructions employed for the hammer assembly makes possible the use of a magnet of short magnetic length and large area which provides eiiicient use of magnetic materials having a high coercive force, and permits theluse of permanent magnet material which is relatively weak physically.

It will be evident` that various modifications canL be` made to the described embodiments without departing from the scope of the present` invention.

I claim as my invention:

l. A magnetic hammer comprising a head composed between opposed portions of said magnet having the same magnetic polarity.'

2. A magnetic hammer comprising a head composed of ferromagnetic material, said head having a generally cylindrical recess therein, an annular permanent magnet disposed in said recess, said magnet having a direction of magnetization which is radial with respect to the longitudinal axis of said head, and a ferromagnetic pole piece disposed within saidpermanent magnet.

3. A` magnetic hammer comprising a head composed of ferromagnetic materialV and having a recess in the striking face thereof, a permanent'magnet' structure received in said recess, a spacer between one end of said magnet and said striking face, said spacer having a surface flush with said striking face, said magnet structure being radially magnetized, and a ferromagnetic pole piece extending between opposed portions of similar magnetic polarity in said permanent magnet structure, said pole piece also having an lend surface 'iiush with said' striking face.

4. A magnetichammery comprising a head composed of ferromagnetic material and having a recess in the strikingV face thereof,y a first non-magnetic spacer received at the base of said recess, a4 Second non-magnetic spacer disposed at the'opposite end of said recess, a permanent magnet disposed between said spacers and including a space between opposed portions thereof, said magnet beingv radially magnetize'd, and a ferromagnetic pole piece situated in said space and providing a low reluctance .path from said opposed portions.

5. A magnetic hammer comprising a head composed of ferromagneticmaterial` and having a recess in the striking face thereof, a first non-magnetic spacer received at the base of said recess,1a second non-magnetic spacer disposedat the opposite end of said recess, a permanent magnet disposed between said spacers and inclndinga space betweenopposedportions thereof, said magnet being radially magnetized and a ferromagnetic pole piece situated in said space and providing alow reluctance path from said opposed portions, said second spacer and said pole piece having coplanarfaces defining a striking face forsaid hammer.

6. A magnetic hammer comprising a head composed of ferromagnetic material, said head having a recess therein, a permanent magnetcomprising barium ferrite disposed in said recess, said magnet having a direction of magnetization which is radial with respect to the` longitudinal axis of said head, and a ferromagnetic pole piece disposed within said permanent magnet between sur faces of the samel magnetic polarity and providing a low reluctance path for Said magnet.

7. A magnetic hammer comprising a head co r rlposed of ferromagnetic material, said head having a recess therein rearwardly from the striking face thereof, a pair of flat permanent magnets 'both -in spaced relation within saidre'cess, said( magnets being magnetizedv'in a direction which Vis radialwith respect to thelongitudinal axisof said head, a spacer between one 4end of said magnet and said striking face, said spacer having a surface ush, with` said striking face, and a ferromagnetic pole piece disposed inthe space between said magnets, said pole piece also having an end surface flush with said striking face.

References Cited in'the'file of this patent UNiTEn STATES PATENTS 2,671,483 clark Mar. 9; 1954 FOREIGN PATENTS 801,446 Germany lan. 8, 1951 1,115,035 France' Dec. 26,"1955 

